| 摘要 |
PURPOSE:To simply measure a clean air state from a remote place, by opposing the end parts of a pair of the optical fibers, which are respectively optically connected to a light emitting element and a light detecting element, in a separated state to expose said end parts to gas to be measured. CONSTITUTION:A light emitting element 2 is connected to one end of an optical fiber 10A and a light detecting element 3 is connected to one end of an optical fiber 10B and the other ends of the optical fibers 10A, 10B are opposed to be exposed to the gas stream to be measured in a clean bench 4. When dust traverses the light path between the optical fibers, a part of light is blocked and the level of the output electric signal of the light detecting element 3 is lowered. The number of times of the lowering in this level are counted by a comparing circuit 5, an amplifying circuit 6 and a counter circuit 7. The count result of the counter circuit 7 is displayed on a display part and recorded on a recording part 9. |
